According to the prior art shown in FIG. 1, a heat transfer fluid loop, used to cool a heat source 41, comprises:
1) a closed conduit in which a diphasic fluid flows,
2) a heat exchanger 10, known as an evaporator, that carries out heat exchange between the fluid and the heat source, and
3) a heat exchanger 61, known as a condenser, that carries out heat exchange between the fluid and a heat sink 60 for cooling.
The diphasic fluid used is generally in the mainly liquid state in the cold part of the loop, and in the mainly gaseous state in the hot part thereof.
A typical heat source is formed for example by an item of dissipative electronic equipment, and a typical heat sink is formed for example by a radiator in contact with an environment that is colder than the heat source or else by a thermodynamic cycle machine, for example a Stirling cycle machine, that produces cold from electrical energy.
More generally, a heat source may be formed by an element that is not necessarily electronic and is heated by items of dissipative electronic equipment or by elements outside the system. This is the case for example when a set of items of electronic equipment is fastened to a support structure, optionally by distributing the heat emitted by the items of equipment to the structure as a whole by means of heat pipes or any other device for this purpose. In this case, the heat source to be considered is the assembly formed by the support structure and the items of equipment, and the heat exchanger of the heat transfer fluid loop may be positioned either on a particular item of equipment or on the support structure. It is also possible to bear in mind that simple structural elements that are illuminated by the sun (such as baffles for example) may form heat sources.
In the more particular field of fluid loops in which the fluid is pumped by capillarity (known as a “capillary fluid loop”), the evaporator 10 may advantageously comprise a reserve 70 (see FIGS. 1 and 7) of fluid in the diphasic liquid/vapor state (in the case of a fluid loop known as a “loop heat pipe”) and in all cases a porous mass 80, or advantageously a microporous mass (pores having a micrometric size), for pumping the liquid by capillarity.
The reserve of liquid, known as a reservoir 70, is located close to the microporous mass in order to provide it with liquid. The liquid present in the reservoir is pumped through the microporous mass, which is positioned as close as possible to the heat source. The liquid vaporizes mainly in this region, and the vapor 91 thus created is evacuated through a conduit toward the heat sink, wherein it condenses in the region of the condenser and then returns toward the evaporator in a partially or completely liquid form 92 through another conduit in order to create a heat transfer cycle.
For its part, the condenser may be formed simply by the conduit that conveys the fluid, generally a simple tube, to which a device (for example a soleplate) for reinforcing heat exchange between the conduit and the heat sink is added.
When a plurality of separate and spaced-apart heat sources are intended to be cooled, the prior art (for example US2011/0056225) suggests the use of as many fluid loops as the heat sources, or suggests multiplying the capillary evaporators on parallel circuits. A fluid loop evaporator is positioned in contact with each heat source and is connected to a radiator in order to evacuate the heat from the heat source. There are thus as many evaporators and fluid loops as there are heat sources.